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MDEV-32771 Server crash upon online alter with concurrent XA

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In case of a non-recovery XA rollback/commit in the same connection,
thon->rollback is called instead of rollback_by_xid, Though previously,
thd_ha_data was moved to thd->transaction->xid_state.xid in hton->prepare.

Like it wasn't enough, XA PREPARE can be skipped upon user and thus we
can end up in hton->commit/rollback with and unprepared XA, so checking
xid_state.is_explicit_XA is not enough -- we should check
xid_state.get_state_code() == XA_PREPARED, which will also guarantee
is_explicit_XA() == true.
This commit is contained in:
Nikita Malyavin
2023-11-13 15:28:19 +01:00
parent f7646d890b
commit d59d883631
3 changed files with 257 additions and 6 deletions
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110
mysql-test/main/alter_table_online_debug.result
View File

@ -1675,6 +1675,116 @@ connect con1, localhost, root,,;
connection default;
drop table t;
set debug_sync= reset;
# MDEV-32771 Server crash upon online alter with concurrent XA
create table t (a int primary key);
insert t values(1),(2),(3);
# First, check that nothing from the rollbacked statement commits
set debug_sync= 'alter_table_online_downgraded signal downgraded wait_for go';
alter table t add b int default (555), algorithm=copy;
connection con1;
set debug_sync= 'now wait_for downgraded';
xa start 'xid';
update t set a = 0;
ERROR 23000: Duplicate entry '0' for key 'PRIMARY'
xa end 'xid';
xa prepare 'xid';
xa commit 'xid';
set debug_sync= 'now signal go';
connection default;
select * from t;
a b
1 555
2 555
3 555
set debug_sync= 'alter_table_online_downgraded signal downgraded wait_for go';
alter table t add c int default(777), algorithm=copy;
connection con1;
set debug_sync= 'now wait_for downgraded';
xa start 'xid';
update t set a = 0;
ERROR 23000: Duplicate entry '0' for key 'PRIMARY'
xa end 'xid';
xa prepare 'xid';
xa rollback 'xid';
set debug_sync= 'now signal go';
connection default;
select * from t;
a b c
1 555 777
2 555 777
3 555 777
# Same, but add one successful statement into transaction
set debug_sync= 'alter_table_online_downgraded signal downgraded wait_for go';
alter table t drop b, algorithm=copy;
connection con1;
set debug_sync= 'now wait_for downgraded';
xa start 'xid';
update t set a = 10 where a = 1;
update t set a = 0;
ERROR 23000: Duplicate entry '0' for key 'PRIMARY'
xa end 'xid';
xa prepare 'xid';
xa rollback 'xid';
set debug_sync= 'now signal go';
connection default;
select * from t;
a c
1 777
2 777
3 777
set debug_sync= 'alter_table_online_downgraded signal downgraded wait_for go';
alter table t drop primary key, algorithm=copy;
connection con1;
set debug_sync= 'now wait_for downgraded';
xa start 'xid';
# This statement will take effect.
update t set a = 10 where a = 1;
update t set a = 0;
ERROR 23000: Duplicate entry '0' for key 'PRIMARY'
xa end 'xid';
xa prepare 'xid';
xa commit 'xid';
set debug_sync= 'now signal go';
connection default;
select * from t;
a c
10 777
2 777
3 777
# The only statement succeeds (test both commit and rollback)
set debug_sync= 'alter_table_online_downgraded signal downgraded wait_for go';
alter table t add d text default ('qwe'), algorithm=copy;
connection con1;
set debug_sync= 'now wait_for downgraded';
xa start 'xid';
update t set a = 0;
xa end 'xid';
xa prepare 'xid';
xa rollback 'xid';
set debug_sync= 'now signal go';
connection default;
select * from t;
a c d
10 777 qwe
2 777 qwe
3 777 qwe
set debug_sync= 'alter_table_online_downgraded signal downgraded wait_for go';
alter table t drop c, algorithm=copy;
connection con1;
set debug_sync= 'now wait_for downgraded';
xa start 'xid';
update t set a = 0;
xa end 'xid';
xa prepare 'xid';
xa commit 'xid';
set debug_sync= 'now signal go';
connection default;
select * from t;
a d
0 qwe
0 qwe
0 qwe
drop table t;
set global default_storage_engine= MyISAM;
disconnect con1;
disconnect con2;

119
mysql-test/main/alter_table_online_debug.test
View File

@ -1922,6 +1922,125 @@ select * from t;
--connection default
drop table t;
set debug_sync= reset;
--echo # MDEV-32771 Server crash upon online alter with concurrent XA
create table t (a int primary key);
insert t values(1),(2),(3);
--echo # First, check that nothing from the rollbacked statement commits
set debug_sync= 'alter_table_online_downgraded signal downgraded wait_for go';
send alter table t add b int default (555), algorithm=copy;
--connection con1
set debug_sync= 'now wait_for downgraded';
xa start 'xid';
--error ER_DUP_ENTRY
update t set a = 0;
xa end 'xid';
xa prepare 'xid';
xa commit 'xid';
set debug_sync= 'now signal go';
--connection default
--reap
select * from t;
set debug_sync= 'alter_table_online_downgraded signal downgraded wait_for go';
send alter table t add c int default(777), algorithm=copy;
--connection con1
set debug_sync= 'now wait_for downgraded';
xa start 'xid';
--error ER_DUP_ENTRY
update t set a = 0;
xa end 'xid';
xa prepare 'xid';
xa rollback 'xid';
set debug_sync= 'now signal go';
--connection default
--reap
select * from t;
--echo # Same, but add one successful statement into transaction
set debug_sync= 'alter_table_online_downgraded signal downgraded wait_for go';
send alter table t drop b, algorithm=copy;
--connection con1
set debug_sync= 'now wait_for downgraded';
xa start 'xid';
update t set a = 10 where a = 1;
--error ER_DUP_ENTRY
update t set a = 0;
xa end 'xid';
xa prepare 'xid';
xa rollback 'xid';
set debug_sync= 'now signal go';
--connection default
--reap
select * from t;
set debug_sync= 'alter_table_online_downgraded signal downgraded wait_for go';
send alter table t drop primary key, algorithm=copy;
--connection con1
set debug_sync= 'now wait_for downgraded';
xa start 'xid';
--echo # This statement will take effect.
update t set a = 10 where a = 1;
--error ER_DUP_ENTRY
update t set a = 0;
xa end 'xid';
xa prepare 'xid';
xa commit 'xid';
set debug_sync= 'now signal go';
--connection default
--reap
select * from t;
--echo # The only statement succeeds (test both commit and rollback)
set debug_sync= 'alter_table_online_downgraded signal downgraded wait_for go';
send alter table t add d text default ('qwe'), algorithm=copy;
--connection con1
set debug_sync= 'now wait_for downgraded';
xa start 'xid';
update t set a = 0;
xa end 'xid';
xa prepare 'xid';
xa rollback 'xid';
set debug_sync= 'now signal go';
--connection default
--reap
select * from t;
set debug_sync= 'alter_table_online_downgraded signal downgraded wait_for go';
send alter table t drop c, algorithm=copy;
--connection con1
set debug_sync= 'now wait_for downgraded';
xa start 'xid';
update t set a = 0;
xa end 'xid';
xa prepare 'xid';
xa commit 'xid';
set debug_sync= 'now signal go';
--connection default
--reap
select * from t;
drop table t;
eval set global default_storage_engine= $default_storage_engine;
--disconnect con1

34
sql/online_alter.cc
View File

@ -315,17 +315,39 @@ int online_alter_savepoint_rollback(handlerton *hton, THD *thd, sv_id_t sv_id)
static int online_alter_commit(handlerton *hton, THD *thd, bool all)
{
int res= online_alter_end_trans(get_cache_list(hton, thd), thd,
ending_trans(thd, all), true);
cleanup_tables(thd);
int res;
bool is_ending_transaction= ending_trans(thd, all);
if (is_ending_transaction
&& thd->transaction->xid_state.get_state_code() == XA_PREPARED)
{
res= hton->commit_by_xid(hton, thd->transaction->xid_state.get_xid());
// cleanup was already done by prepare()
}
else
{
res= online_alter_end_trans(get_cache_list(hton, thd), thd,
is_ending_transaction, true);
cleanup_tables(thd);
}
return res;
};
static int online_alter_rollback(handlerton *hton, THD *thd, bool all)
{
int res= online_alter_end_trans(get_cache_list(hton, thd), thd,
ending_trans(thd, all), false);
cleanup_tables(thd);
int res;
bool is_ending_transaction= ending_trans(thd, all);
if (is_ending_transaction
&& thd->transaction->xid_state.get_state_code() == XA_PREPARED)
{
res= hton->rollback_by_xid(hton, thd->transaction->xid_state.get_xid());
// cleanup was already done by prepare()
}
else
{
res= online_alter_end_trans(get_cache_list(hton, thd), thd,
is_ending_transaction, false);
cleanup_tables(thd);
}
return res;
};